PNEUMATIC TIRE AND PNEUMATIC TIRE SET

摘要

A pneumatic tire, for which noises of passage are decreased while draining performance being maintained on a directional tread pattern, and a pneumatic tire set. Arranged on a tread surface, for which a direction of tire revolution is indicated, alternately in a circumferential direction of a tire are groups of rightwardly inclined grooves, each group composed of a unit of grooves starting at a tread center portion and inclining in a direction opposite to the direction of tire revolution to pass through a rightward shoulder edge, and groups of leftwardly inclined grooves, each group composed of a unit of grooves starting at the tread center portion and inclining in the direction opposite to the direction of tire revolution to pass through a leftward shoulder edge. Formed on the tread center portion are a single, main rib, which is defined zigzaggedly in a circumferential direction of the tire by starting ends of the groups of rightwardly inclined grooves and the groups of leftwardly inclined grooves, and sub-ribs branching off the main rib along the groups of rightwardly inclined grooves and the groups of leftwardly inclined grooves. Further, noises are decreased by lessening a groove area ratio for a tire for rear wheels, and providing small grooves at variable pitches on the sub-ribs of a tire for idler wheels.